OOo Purdybear. I love dreams. They tell us so much about ourselves, in overt and more subtle ways too.
Do you dream in black and white, or in colour? How do your dreams make you feel, and what is the overall thought in your mind when you wake from an important dream?
I know what cats signify to me personally, and that's where the magic of dreams comes into being. Each dream will mean different things for different individuals according to their own ambitions, fears and feelings.
If I were interpreting your dream off the cuff, I would say that there are three important component parts:
The Building
Buildings represent our conscious, subconscious and unconscious selves. Generally, the higher the building, the more the dream relates to our unconscious - the intuitive drive that pushes us forward. In this instance, the high rise block of flats represents a lofty ideal - one which you think is unachievable (possibly owning a cat again? Possibly something else you feel needs to be put right in your life)
The fact this block of flats is destined for demolition suggests to me your way of thinking is changing - you question what you have always accepted before, the old is making way for the new - the ground is being cleared. You are looking to change old beliefs and long held social mores.
You know this is possible, and you're searching for the truth. The guinea pig represents an image of something non threatening and innocuous. The guinea pig represents something which can be held - accommodated - comfortably within your hands. An achievable ideal. Your Father is offering reassurance by his presence in your dream. He is someone you trust, who is helping you to "search" for the truth. The flat which you bought was clean, and therefore you know in your subconscious (the middle ground) that the goal you seek is achievable.
The cats
These are your aim - your reward. The "rescue" - not just of the cats, but of something within yourself which is currently absent. A need which has to be met. You've pictured those cats. You've given shape and definition to something which previously was abstract and unknown - you didnt know what the cats looked like, just that they existed "in potentia." The sitting room represents the heart of the matter - the place where you feel comfortable. You found the cats where you would expect to find comfort and ease.
You then managed to evacuate them - in effect, bringing them closer to your own reality.
The rest
Your Father was helping you - from the past - to let go of past thought processes, and to accept that new things can be brought out of old beliefs. In a way, irrespective of whether or not this dream is an indirect way of telling you that you can perhaps become a cat owner again, fulfilling a very real desire that you have, it is almost certainly telling you that old patterns of behaviour can be released, and that good can come out of situations which seem lost (the flats which are due to be demolished.) You have inner courage (rescuing something you care deeply about) and can achieve things you felt may have been beyond your reach (you make it out with the cats). Old things are being cleared away, ready for new things to come into your life. Emotional rescue as well as physical rescue. Giving visual clothing to the cats you perceived, means that you can at last make room for these new things to come into your life, and visualise how this can become real.
Whether or not this is a literal manifestation of cats in your life, or of something else which is going on in your life is something you can know best, but whatever it is, it seems to me like you're making very real progress towards a goal you previously felt was out of reach.